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Posted to jira@arrow.apache.org by "Andrew Lamb (Jira)" <ji...@apache.org> on 2021/04/26 13:34:02 UTC
[jira] [Closed] (ARROW-12293) [Rust][DataFusion] Word Count
[ https://issues.apache.org/jira/browse/ARROW-12293?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andrew Lamb closed ARROW-12293.
-------------------------------
Resolution: Invalid
> [Rust][DataFusion] Word Count
> -----------------------------
>
> Key: ARROW-12293
> URL: https://issues.apache.org/jira/browse/ARROW-12293
> Project: Apache Arrow
> Issue Type: Wish
> Components: Rust - DataFusion
> Reporter: Jacob Baumbach
> Priority: Trivial
> Labels: newbie, question
>
> I am learning DataFusion and tried to do the canonical big data version of hello world, word count, using DataFusion. I have been unsuccessful, and I am wondering if word count is even currently possible with DataFusion.
>
> Typically word count involves a flat_map where you split each string based on the white space contained within each string.
>
> There are two issues I am running into
> 1) creating a udf that goes from &str -> Vec<&str>. I cannot find an `arrow::array` that maps to a collection of string, which is preventing me from creating a udf that can perform the split.
> 2) Assuming I could get `1` to work, I am not aware of a method that is similar to flat_map that may be performed on a column. In sql, I believe this is called `explode`, which I can't find in the codebase, which makes me think flat_map style operations aren't possible.
>
> My questions are:
> Is word count currently possible in DataFusion? If so, how can perform the split and how can you perform a flat_map? If word count cannot be done, what would need to be implemented to make it possible?
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